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- Title
Improved Crop Canopy and Water Balance Dynamics for Agroecosystem Modeling Using DayCent.
- Authors
Yao Zhang; Paustian, Keith; Suyker, Andrew
- Abstract
Field experimental data of maize and soybean from two locations in the US Corn Belt and winter wheat in northern Oklahoma were used to develop a modified empirical method for simulating green leaf area index (GLAI) in the DayCent model. The method is based on the change of green leaf weight ratio (GLWR) as a function of phasic development in grain crops, in which GLWR decreases as growing degree days increase. In the previous version of DayCent, GLWR was assumed constant for annual crops and GLAI increased proportional to above-ground biomass from post-emergence until reaching full canopy and was then assumed to remain constant until harvest. The simulated results from the modified DayCent model compared well with field measurement of GLAI and aboveground biomass for all three crops (avg. R² of approximately 0.8). The new GLAI algorithm yielded a substantial improvement in simulated canopy dynamics as well as evapotranspiration and soil-water content, especially in late growing season period, with the improved representation of canopy senescence. The overall R² for canopy cover improved from 0.66 to 0.93 for maize and 0.52 to 0.88 for soybean; the R² for weekly ET in late growing season increased from 0.53 to 0.82 for the Nebraska site. Simulation of biomass and grain yield by the modified model was also improved relative to the prior DayCent version for maize (R² increased from 0.47 to 0.69).
- Subjects
WATER balance (Hydrology); AGRICULTURAL mathematics; EMPIRICAL research; AGRICULTURAL research; CORN; STATISTICAL sampling
- Publication
Agronomy Journal, 2018, Vol 110, Issue 2, p511
- ISSN
0002-1962
- Publication type
Article
- DOI
10.2134/agronj2017.06.0328